explain find_in_set

The `FIND_IN_SET` function is a MySQL function that searches for a value within a comma-separated list of values. It takes two arguments: the value to search for and the comma-separated list to search within.

The function returns the position of the value within the list if found, or 0 if not found. The position is determined by the order in which the values appear in the list.

Here's an example to illustrate its usage:

SELECT FIND_IN_SET('apple', 'apple,banana,grape');

In this example, the value 'apple' is searched within the list 'apple,banana,grape'. Since 'apple' is the first value in the list, the function will return 1.

Please note that the `FIND_IN_SET` function is case-sensitive, meaning it treats uppercase and lowercase letters as distinct values.